In plan the store has a curved, plectrum-shaped form and consists mainly of a single-storey sales floor which is 80 metres wide and 40 metres deep.
The roof, an almost imperceptible barrel-vaulted curve to a radius of 280 metres, is covered with stuccoembossed mill-finished aluminium with standing seams. It is highly insulated with a double layer of mineral-fibre thermal insulation on structural liner trays. It is supported by a series of horizontal plate girders and curved 610 x 235mm universal beams as rafters.
The roof curve is punctuated by eight saw-tooth north-facing rooflights on 'hockey-stick' universal beam structures, which run above the curved rafters. To reduce brightness contrast between roof glazing and the adjacent ceiling, the rafters are encased with curved stove-enamelled aluminium cladding panels.
The rooflights are doubleglazed units in aluminium frames, with external aluminium louvres fixed to the face of the glazing mullions.
They drain into composite gutters, wide and strong enough to be walked on which give access to the rooflights for cleaning the glass and maintenance of louvres and the dampers - the automatic opening ventilation and smoke extract units at the head of the saw-tooth.
A similar gutter runs at the curved eaves; it is trimmed with a bull-nosed edge panel of stucco-embossed mill-finished aluminium.At the east and west sides the building is insulated by earth banks; at the top of the banks the roof is protected by a canted stainless steel balustrade.
The main entrance, to the south side, has an overhanging aluminium-covered roof trimmed with an aluminium brise-soleil.